Release govoplan-reporting v0.1.21: preserve calculated measure bindings

src/govoplan_reporting/backend/postgres_planner.py

@@ -344,7 +344,9 @@ def _calculated_sql(
         return _calculated_sql(
             target.expression,
             parameters,
-            prefix + "_" + reference,
+            # The expression position already makes this prefix unique. Model
+            # keys may contain dots or hyphens, which are not SQL bind names.
+            prefix + "_ref",
             measures=measures,
             stack=(*stack, reference),
         )